JPH06112027A - Manufacture of high-quality magnet material - Google Patents

Abstract

PURPOSE:To manufacture a low-cost material for high-quality R-Fe-B magnets relatively easily. CONSTITUTION:This high characteristic magnet material is manufactured by the method, wherein a molten alloy mainly comprising 12-19 at% of R (R represents at least one kind of rare earth element including Y), 5-8.5 at% of B5 and 72.5-82.5at% of Fe is homogenized by heat-treatment at the temperature of 900 deg.C-1150 deg.C, next the particles produced by fine crushing the alloy are molded in a magnetic field to be processed at the temperature of 600-1000 deg.C in hydrogen and then sintered within the temperature range of 1000 deg.C-1150 deg.C in vacuum of Ar inert gas atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new method for producing a Fe-BR high-performance magnet material containing Fe, B and R (rare earth elements) as main components, and particularly to a maximum energy product (BH) _max.
The present invention relates to a manufacturing method for easily obtaining a Fe-BR type permanent magnet having high characteristics of 40 MGOe or more.

[0002]

2. Description of the Related Art In recent years, various inexpensive and high-performance Fe-BR magnet materials have been developed as permanent magnet materials containing no or essential samarium and cobalt, which are expensive.

For example, after an alloy of composition Fe-BR is produced by high frequency melting, heat treatment (solution treatment or homogenization treatment)
And then coarsely pulverize. After finely pulverizing this to a size of several microns with a jet mill or the like, this fine powder is molded in a magnetic field, sintered in a vacuum, and further aged to obtain a magnet (see JP-A-61-295342). ). An example thereof will be shown as a conventional method 1 later.

Further, for example, in JP-A-62-23902, R (R is at least one of Nd and Pr is 80
%, And the balance is at least one of rare earth elements including Y excluding Nd and Pr) 12 to 19 at%, B 5.5 to
Disclosed is an R-Fe-B type tetragonal alloy powder containing 8.5 at% and Fe 72.5 to 82.5 at% as main components and containing substantially no Fe soft magnetic phase and undergoing H ₂ storage collapse. .
This is, for example, 200 Torr after the solution treatment of the conventional method 1 described above.
It can be obtained by hydrogenating at a pressure of up to 50 kg f / cm ² to occlude hydrogen, allowing it to spontaneously disintegrate, then dehydrogenating, and then similarly subjecting it to coarse pulverization and fine pulverization. An example thereof will be shown as Conventional Method 2 later. This alloy is dominated by R ₂ Fe ₁₄ B tetragonal crystal and contains a very small amount of non-magnetic grain boundary phase. When this powder is used, the maximum energy product is 40M.
High-performance magnets of GOe or better have been obtained.

Further, according to US Pat. No. 4,898,625, a powder obtained by separately producing a quenched ribbon powder having a composition of a main phase R ₂ Fe ₁₄ B and a liquid phase at the time of sintering, and mixing and grinding the powder. A magnet having a high energy product can be obtained relatively easily by molding, sintering, and heat treatment. An example of the manufacturing method is shown as a conventional method 3 later.

According to these conventional techniques, high-performance permanent magnets can be obtained, but each has the following drawbacks.

For example, in the case of the conventional methods 1, 2, and 3, the magnets both have a structure in which the main phase R ₂ Fe ₁₄ B is surrounded by the R-rich phase. In terms of the mechanism of coercive force generation, this R
-The existence of a rich phase is essential. Since the R-rich phase is a non-magnetic phase, the potential of the main phase is diluted by the amount of the R-rich phase to form a magnet. Therefore, a very high (BH) _max cannot be expected.

Further, according to the latter, it is necessary to separately prepare a rapidly cooled ribbon powder having the same composition as the liquid phase at the time of sintering, and it becomes complicated, and its manufacturing equipment is considerably large-scale, and especially mass production. Would incur a significant cost increase.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above problems and to manufacture a magnet material having particularly high characteristics in an R-Fe-B based rare earth magnet relatively easily and at low cost. Is to provide a method.

The objects are as follows: R (R is at least one kind of rare earth element containing Y) 12 to 19 at%, B 5.5 to 8.
After homogenizing a molten alloy containing 5 at% and Fe72.5 to 82.5 at% as a main component by heat treatment at 900 ° C. or higher and 1150 ° C. or lower, and finely pulverizing the alloy, the obtained powder was molded in a magnetic field. This is treated in hydrogen at a temperature of 600 to 1000 ° C. and then in a vacuum or an inert atmosphere at 1000 ° C. to 1150 ° C.
This is achieved by a method for producing a high-performance magnetic material, which is characterized by sintering in a temperature range of ° C.

The present invention will be described in detail. Electrolytic iron, a ferroboron alloy having a certain proportion of boron, and a rare earth element are used as a starting material, and an alloy is prepared by melting and casting at high frequencies. As the rare earth element (R), for example, Nd, Pr, Dy, etc. are preferably used, and particularly Nd is often used. These may be used alone or in combination of two or more kinds.

The alloy thus obtained has α as a primary crystal.
-Precipitate the Fe phase. Even if the alloy is pulverized in the presence of the α-Fe phase, the α-Fe phase is viscous, so that it is difficult to finely pulverize the alloy, which adversely affects the orientation and the sinterability, that is, the improvement of the characteristics. Furthermore, since the α-Fe phase is a ferromagnetic phase, if it remains after sintering, it may become a source of reverse magnetic domains and the coercive force may be very small. A homogenization treatment is performed to remove the α-Fe phase by heat treatment. If the heat treatment temperature is 900 ° C. or lower, there is no effect, and if it is 1150 ° C. or higher, the main phase R ₂ Fe ₁₄ B compound is decomposed.
Perform at a temperature in the range of ˜1150 ° C.

The alloy thus homogenized is crushed by a crusher such as a jet mill to a size of 10 μm or less, preferably 2-3.
Finely pulverize to μm.

After molding this fine powder in a magnetic field, it is treated in hydrogen at a temperature of 600 to 1000 ° C. 6 in hydrogen
By treating at a temperature of 00 to 1000 ° C., the main phase R ₂
Fe ₁₄ B decomposes into RH ₂ , Fe ₂ B and α-Fe.

This decomposition does not occur when the H ₂ gas pressure is less than 10 Torr. Also, if it exceeds 50 kg f / cm ² , it is not preferable from the viewpoint of safety of equipment and work, so 10 Torr to 50 kg
/ Cm ² is preferable. 1 kg f / cm for mass production
^{2 to} 10 kg f / cm ² is more preferable.

After the molded body is heat-treated in hydrogen, it is heated in a vacuum or an inert atmosphere, particularly an Ar inert atmosphere, and sintered.
In this process, dehydrogenation occurs and at the same time, a reaction occurs in which the decomposed material returns to the original main phase. At this time, very fine crystals of the main phase are deposited, but it is possible to perform dense sintering while maintaining these fine crystal grains.

If the temperature is lower than 1000 ° C., a high density sintered body cannot be obtained, and if the temperature exceeds 1150 ° C., the main phase R ₂ Fe ₁₄ B is decomposed. Therefore, it sinters in the temperature range of 1000 ° C-1150 ° C.

In the sintered body thus obtained, the main phase is precipitated in a state close to the size of a single magnetic domain, so that the coercive force generating mechanism is a pinning type and there is no R-rich phase. Has a structure that generates a coercive force. Therefore, even if the composition is close to the main phase, it is magnetized, so that a magnet material having particularly high characteristics can be obtained.

The starting alloy composition is a condition for obtaining a high energy product of 40 MGOe or more. When the rare earth R is less than 12 at%, the coercive force sharply decreases, and when it exceeds 19 at%, the residual magnetic flux density (Br) decreases, and the required excellent characteristics cannot be obtained. Therefore, R is 12 to 19 at%.
And

When B <5.5 at%, coercive force and squareness are deteriorated, and when B> 8.5 at%, Br is decreased, and excellent magnet characteristics cannot be obtained, so B is 5.5. ~ 8.5 at
%.

When Fe <72.5 at%, Br decreases,
Further, when Fe> 82.5 at%, the coercive force is drastically reduced, so Fe is set to 72.5 to 82.5 at%.

Further, by substituting a part of Fe with Co up to 30 at%, the Curie point Tc of the magnet can be raised and the temperature characteristic can be improved, which is effective.
Further, in the present invention, a part of Fe is used to improve coercive force.
2 at% or less of Ti, V, Cr, Ga, Zr, Hf, N
At least one of b, Ta, Mo, W, Al and Si can be substituted, but in general, these additive elements tend to decrease the residual magnetic flux density Br, and when the amount of substitution exceeds 2 at%, the amount of Br It is not preferable because the decrease becomes remarkable. The preferable amount of the additional element is about 0.1 to 1 at%.

[0023]

EXAMPLES Examples and reference examples of the present invention will be given below. In each example, as a starting material, electrolytic iron having a purity of 99.8%, B 20.8 wt% are contained, and the balance is a ferroboron alloy containing impurities such as Fe and C, and a rare earth element having a purity of 99.6% or more. Using. (Example 1) <Invention> After alloys having compositions 1-1, 2, and 3 shown in Table 1 were prepared by high-frequency melting, they were homogenized by heat treatment at 1100 ° C for 24 hours in a vacuum, and then once. After roughly pulverizing to 35 mesh through with a jaw crusher, this was finely pulverized with a jet mill in an N ₂ gas stream to 3 μ.

Next, this fine powder was subjected to 1 in a magnetic field of 10 KOe.
After molding with a molding pressure of t / cm ² , after processing for 3 hours at a temperature of 800 ° C. in a H ₂ gas 1 kg f / cm ² flow, it was vacuumed for 11 hours.
A magnet was produced by sintering at 20 ° C. for 3 hours. <Conventional method> For comparison, the molded body obtained in the same process as the present invention was sintered at 1120 ° C for 3 hours in vacuum without H ₂ gas treatment, and then subjected to aging treatment at 570 ° C for 2 hours in vacuum. The applied magnet was produced (conventional method 1).

Table 1 Composition No. Alloy composition 1-1 Nd ₁₃ Fe ₈₀ B ₇ 1-2 Pr ₁₄ Fe ₇₉ B ₇ 1-3 (Nd _0.9 Dy _0.1 ) ₁₃ Fe ₈₁ B ₆ Table 2 shows the magnet characteristics obtained by the <present invention> and <conventional method>.
Shown in.

Table 2 _{(BH) max} Composition No. Method Br (KG) iHc (KOe) bHc (KOe) (MGOe) 1-1 Present Invention 14.4 10.1 9.3 49.0 Conventional method 13.6 6.2 6.0 38.0 1-2 The present invention 14.0 9.9 8.5 46.7 Conventional method 13.1 5.8 5.5 5.5 35.5 1-3 The present invention 14.1 10.3 9.8 48.3 Conventional method 13.0 6.6 6.1 36.0 From the above results, it is understood that by using the method of the present invention, a magnet having higher Br, iHc, and (BH) _max can be obtained as compared with the conventional method. (Example 2) After the alloys shown in Table 3 were prepared by high-frequency melting, the alloy was homogenized by heat treatment in vacuum at 1100 ° C for 24 hours, and the subsequent steps were (Example 1) <present invention>.
Under the same conditions as described above, pulverization, forming in a magnetic field, H ₂ treatment, and sintering were performed to produce a magnet.

Table 3 also shows the obtained magnet characteristics.
Composition No. In the cases of 3-1 and 3-7 and 3-10, the regulations are not met and the magnetic characteristics are insufficient.

For example, in the case of composition 3-1 Nd = 11.8
The coercive force of the obtained magnet is 0, and therefore the maximum energy product is also 0. In the case of composition 3-7, Nd = 20 is more than specified, and in case of composition B = 5.2, it is less than specified, and in case of composition 3-10, B = 8.8 is more than specified. The maximum energy products of the magnets obtained are 38.5 and 38.3 (MGOe), respectively, and neither of them has the target maximum energy product of 40 MGOe. However, magnets having other compositions have the compositions specified in the present invention, and the respective target magnets are 40 MG.
The maximum energy product of Oe is obtained, and other magnetic properties are sufficient.

From the above results, it can be seen that by using the method of the present invention, a high energy product magnet of 40 MGOe or more can be obtained in the following composition range.

12 ≦ Nd ≦ 19 at% 5.5 ≦ B ≦ 8.5 at% 72.5 ≦ Fe ≦ 82.5 at% Table 3 Composition Magnet alloy composition (at%) Magnetism Characteristics No. Nd Fe B Br (KG) iHc ^(KOe) (BH) max ^(MGOe) 3-1 11.8 82.4 5.9 15.5 0 0 3-2 12.0 82.1 5.9 15.1 7.1 7.1 45.6 3-3 12.5 81.7 5.8 14.8 8.8 53.0 3-4 15.0 79.3 5.7 14.0 12.0 46.1 3-5 17.0 77.5 5.6 13.6 12.7 42.2 3-6 19.0 75.6 5.5 13.2 13.0 40.0 3-7 20.0 74.7 5.2 5.2 13.1 13.3 38.5 3-8 14.7 78.0 7.3 13.7 8.9 45.5 3-9 12.3 79.4 8.5 13.8 3.8 6.5 42.2 3-10 12.2 79.0 8.8 13.3 5.8 38.3 (Reference Example) The magnet according to the present invention obtained with the composition No. 3-3 of (Example 2) was compared with other conventional magnets. The following 3 known
Two methods were used for comparison.

(Conventional method 1) Composition Nd _12.5 Fe _81.7 B _5.8
After manufacturing the alloy of the above by high frequency melting, this is vacuumed at 1100 ℃
After heat treatment for 24 hours, it was roughly crushed to 35 mesh through. Using a jet mill, apply this in an N ₂ stream 3
After finely pulverizing to μ, this fine powder was compacted at a compacting pressure of 1 t / cm ² in a magnetic field of 10 KOe, sintered at 1120 ° C. for 3 hours in vacuum, and then subjected to aging treatment at 570 ° C. for 2 hours in vacuum. A magnet was produced.

(Conventional method 2) Composition Nd _12.5 Fe _81.7 B _5.8
After making the alloy of the above by high frequency melting, this is 1100 ℃ in vacuum
After heat treatment for 24 hours, this is 1Kgf / cm at room temperature.
^After being treated with H ₂ gas pressure of 2 for 2 hours to spontaneously disintegrate by H ₂ occlusion, dehydrogenation treatment was performed in vacuum for 3 hours, and coarsely pulverized to 35 mesh through. In the subsequent step, a magnet was produced by finely pulverizing, molding in a magnetic field, sintering and aging in the same manner as (conventional method 1).

(Conventional method 3) Stoichiometric composition Nd ₂ Fe ₁₄ B
Alloy (main phase alloy) was prepared by high-frequency melting, homogenized by heat treatment in vacuum at 1100 ° C. for 24 hours, and then coarsely pulverized to a size of 35 mesh through.

Next, using a liquid quenching method for Nd elemental metal, 2
Argon gas pressure was applied to the surface of the roll rotating at 0 m / sec by jetting, and high speed cooling was performed, and the rapidly cooled thin strip obtained from this was coarsely pulverized to 35 mesh through.

Next, the main phase alloy powder and the Nd quenched powder were weighed so that the composition was Nd _12.5 Fe _81.7 B _5.8, and V was measured.
Mix with a mold mixer. In the subsequent step, a magnet was produced by finely pulverizing, molding in a magnetic field, sintering and aging in the same manner as (conventional method 1).

The magnet characteristics obtained by the above three conventional methods are shown in Table 4 together with the magnet characteristics obtained by the method of the present invention.

Table 4 (Magnet composition Nd _12.5 Fe _81.7 B _5.8 ) Porcelain characteristic Br (KG) iHc (KOe) bHc (KOe) (BH) max (MGOe) Inventive Method 14.8 8.8 8.5 53.0 Conventional method 1 13.1 3.9 3.7 26.5 Conventional method 2 14.3 7.0 6.8 48.0 Conventional method 3 14.5 7.7 7.4 49.7 From the above, by using the method of the present invention, the magnet characteristics obtained by using the conventionally known method are further improved,
It can be seen that a high energy product is obtained.

[0038]

As is apparent from the above description, according to the method of the present invention, an R-Fe-B system permanent magnet having high magnetic characteristics such as a maximum energy product exceeding 40 MGOe can be easily obtained. Particularly, in the case of the present invention, since hydrogen treatment is performed after finely pulverizing, the target of H ₂ treatment is
Since it becomes a fine powder having a size of μ or less, the H ₂ treatment can be performed at a low pressure, and it becomes possible to use a simple one in terms of equipment and steps.

Further, since the rapid cooling method, which is a costly means, is not used, it is possible to manufacture a high-performance magnet material relatively easily and at a low cost.

Further, the magnet according to the method of the present invention is easily oxidized to R
-High coercive force can be obtained even if the rich phase is as small as possible, and the oxygen content of the sintered body is extremely low due to the reducing action by H ₂ treatment, and anxiety factors such as rust generation and deterioration over time can be reduced. it can.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C22C 33/02 K 38/00 303 D H01F 1/06 (72) Inventor Yuko Murahiro Shimbashi, Minato-ku, Tokyo 5-36-11 Fuji Electric Chemical Co., Ltd. (72) Inventor Tomoyuki Hayashi Shimbashi 5-36-11 Fuji Electric Chemical Co., Ltd. (72) Inventor Yoshiteru Nakagawa Minato-ku, Tokyo Shimbashi 5-36-11 Fuji Electric Chemical Co., Ltd. (72) Inventor Kazuo Matsui 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd.

Claims (1)

[Claims] 1. R (R is at least one of rare earth elements including Y) 12 to 19 at%, B 5.5 to 8.5 at%, Fe7
900 for molten alloys containing 2.5 to 82.5 at% as a main component
After homogenizing by heat treatment at ℃ or more and 1150 ℃ or less, finely pulverizing this alloy, molding powder in a magnetic field, treating this in hydrogen at a temperature of 600 to 1000 ℃, then vacuum or inert A method for producing a high-performance magnetic material, which comprises sintering in a temperature range of 1000 ° C to 1150 ° C in an atmosphere.